ECJ fails to compile method invocation while javac successfully

compiles eclipse-jdt#1591

hapless attempt to mimic javac behavior, causing regressions in
GenericsRegressionTest_1_8.testBug472851()

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/BoundSet.java

@@ -770,6 +770,8 @@ private ConstraintTypeFormula combineSameSameWithProperType(TypeBound boundLeft,
 			InferenceVariable alpha = boundLeft.left;
 			TypeBinding left = boundRight.left; // no substitution since S inference variable and (S != α) per precondition
 			TypeBinding right = boundRight.right.substituteInferenceVariable(alpha, u);
+			if (TypeBinding.equalsEquals(right, boundRight.right))
+				return null; // no new information
 			return ConstraintTypeFormula.create(left, right, ReductionResult.SAME, boundLeft.isSoft||boundRight.isSoft);
 		}
 		return null;

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/ConstraintTypeFormula.java

@@ -112,6 +112,7 @@ public Object reduce(InferenceContext18 inferenceContext) {
 				if (this.left.kind() != Binding.WILDCARD_TYPE) {
 					return ConstraintTypeFormula.create(this.left, this.right, SAME, this.isSoft);
 				} else {
+					// FIXME: with the pending change in BoundSet, removing this might actually help:
 					// TODO: speculative addition:
 					if (this.right instanceof InferenceVariable)
 						return new TypeBound((InferenceVariable) this.right, this.left, SAME, this.isSoft);

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericsRegressionTest_1_8.java

@@ -10682,4 +10682,25 @@ public int getWeaveCount() {
 			"----------\n",
 			null, true, customOptions);
 	}
+	public void testGH1591() {
+		runConformTest(
+			new String[] {
+				"Outer.java",
+				"""
+				import java.io.Serializable;
+				import java.util.List;
+				import java.util.function.Supplier;
+
+				public class Outer {
+					public void test() {
+						Supplier<? extends List<? extends Serializable>> supplier = () -> null;
+						error(supplier.get(), "");
+					}
+
+					public <T, V extends Serializable> void error(List<V> v2, T t) {}
+
+					}
+				"""
+			});
+	}
 }